Methods and compositions for improved ion-exchange chromatography

Abstract

The invention generally relates to ion-exchange chromatography. More particularly, the invention relates to compositions and methods that can substantially improve analytical sensitivity and/or selectivity of ion-exchange chromatography as well its efficiency and quality as a purification or preparation tool.

The invention claimed is: 
     
       1. A method for analyzing or purifying one or more ionic analytes in a sample by anion-exchange chromatography, comprising:
 providing an anion-exchange column packed with an anion-exchange stationary phase; 
 providing an anion-exchange mobile phase having a modifying agent; 
 performing anion-exchange chromatography under a condition allowing anion exchange between the one or more ionic analytes in the sample and the anion-exchange stationary phase, thereby separating the one or more ionic analytes in the anion-exchange column; and 
 analyzing and/or collecting the separated one or more ionic analytes; 
 wherein: 
 the modifying agent is an alkylene oxide oligomer comprising at least three units of an alkylene oxide moiety; and 
 at least one of the one or more ionic analytes comprises a polyethylene-glycol moiety. 
 
     
     
       2. The method of  claim 1 , wherein at least one of the one or more ionic analytes comprises a polyethylene glycol-conjugated oligonucleotide. 
     
     
       3. The method of  claim 2 , wherein the polyethylene glycol-conjugated oligonucleotide comprises from about 3 k Da to about 100 k Da of polyethylene oxide and from about 5 to about 2,000 units of nucleotides. 
     
     
       4. The method of  claim 1 , wherein the modifying agent is an ethylene oxide oligomer. 
     
     
       5. The method of  claim 4 , wherein the ethylene oxide oligomer comprises from about 3 k Da to about 100 k Da of polyethylene oxide. 
     
     
       6. The method of  claim 1 , wherein the modifying agent is present in the anion-exchange mobile phase at a concentration from about 0.1 μM to about 100 μM. 
     
     
       7. The method of  claim 1 , wherein each of the one or more analytes is present in the sample at a concentration from about 0.05 μM to about 500 μM, wherein the concentration is based on the non-conjugated moiety of the analytes. 
     
     
       8. The method of  claim 1 , wherein the sensitivity of anion-exchange chromatography using the anion-exchange mobile phase with the modifying agent is at least 2 fold greater than that of anion-exchange chromatography using the same anion-exchange mobile phase without the modifying agent. 
     
     
       9. A method for performing anion-exchange chromatography comprising adding a modifying agent to a mobile phase prior to performing anion-exchange, wherein the modifying agent is an alkylene oxide oligomer comprising at least three units of an alkylene oxide moiety. 
     
     
       10. The method of  claim 9 , wherein the modifying agent is an ethylene oxide oligomer. 
     
     
       11. The method of  claim 9 , wherein the modifying agent is present in the anion-exchange mobile phase at a concentration from about 0.1 μM to about 100 μM. 
     
     
       12. A method for performing ion-exchange chromatography of a sample comprising an ionic analyte, the method comprising adding as an additive a modifying agent to a mobile phase prior to performing ion-exchange chromatography using the mobile phase, wherein the modifying agent is an alkylene oxide oligomer comprising at least three units of an alkylene oxide moiety and the ionic analyte comprises a polyethylene-glycol moiety. 
     
     
       13. The method of  claim 12 , wherein the ion-exchange chromatography is anion exchange chromatography. 
     
     
       14. The method of  claim 12 , wherein the ionic analyte is a polyethylene glycol-conjugated oligonucleotide or polypeptide. 
     
     
       15. The method of  claim 12 , wherein the alkylene oxide oligomer is an ethylene oxide oligomer. 
     
     
       16. The method of  claim 15 , wherein the ethylene oxide oligomer comprises from about 3 k Da to about 100 k Da of polyethylene oxide.